This invention relates to a fire shielded doorlatch knob assembly for locksets, and more particularly, to a doorlatch knob assembly of somewhat conventional form which has added thereto a most important unique shield of fire resistant material which will protect the integrity of an associated lockset doorlatch mechanism for greater lengths of time and prevent flame penetration thereto for greater lengths of time, as well as to the opposite doorlatch knob assembly of the lockset, in the event of heat destruction of the assembly knob. In certain of its more specific embodiment forms, the unique shield may also be integrated into the doorlatch knob assembly so as to at least aid such assembly in the rotative driving and retainment of the associated spindle, thereby adding to the security of the lockset doorlatch mechanism under the described adverse conditions. Furthermore, the unique fire shielding shield, whether of its more general or specific embodiment form, may be readily adapted for use with the usual plain knob assembly or turnbutton knob assembly forms.
In these more modern times, it is well known that people are becoming much more cognizant of the ever present dangers to human life occasioned by structure fires. Although the danger of fire is always present where any structure is concerned, one prominent area of concern is in residential structures, particularly where multiple residence units are contained within a single structure. As a result of this concern, therefore, a relatively large amount of development work has been expended toward improving the human fire protection in these multiple residence unit structures.
With the multiple residence unit structures, it is apparent that a fire developing in one residence unit will, under normal conditions, readily affect the adjacent units and ultimately will spread to affect those of lesser proximity. Although many improvements have been made in various building materials to retard the advance of flame destruction of walls and other structure components, thereby not only retarding the advance of fire within a given residence unit, but also from one unit to the next, a still further important improvement can be made which to this point in time has not been fully recongnized. That deals with a recommendation by experts in fire protection that improvement efforts must be made for minimizing the dangers to human life from fires in these multiple residence unit structures by confining for as long as possible a fire within one residence unit as to both flames and smoke to that particular unit, thereby providing a greater period of time, even though still possibly relatively short, for the occupants of the other units to be alerted and escape. Furthermore, confining the fire to a single unit for as long as possible will give a greater period of time for the arrival of fire fighting units prior to the entire structure being involved.
It is, therefore, an important goal to confine the flames and smoke within a given single multiple residence unit and one of the major solutions to this goal is to provide fire resistant entry doors for each individual unit. This, however, is still not the entire answer since a fire resistant entry door for an individual unit cannot serve its smoke and flame confinement purposes to that particular unit unless the fire resistant door remains closed. An entry door, of course, is retained closed by the lockset installed therein and such lockset must not only be constructed for retaining the entry door closed under normal conditions and against surreptitious manipulation and entry by intruders, but must also maintain these entry door retainment strengths under the heat and flame conditions which can involve even fire resistant door warpage if the before discussed increased fire protection is to be provided.
Past experience has shown that even though an entry door lockset is not only of sufficient strength to reasonably protect against intruders, but is also of sufficient strength to retain the entry door closed under relatively severe door warpage resulting from a contained heat caused by fire, such has only been true where the integrity of the lockset within the door and its bolt connection to the door frame can be maintained. In many prior instances, such integrity with standard entry door locksets has not been possible of maintainment. The internal residence unit flames and heat quickly attack the lockset inside knob assembly many times releasing the lockset bolt and permitting the door warpage to force or "pop" the door open. Even though the bolt mechanism internally of the door is such that the bolt will be retained engaged with the door frame even with a destruction of the lockset internal knob and its immediate mounting components, if there is a direct path exposed for flames to directly contact the bolt mechanism, this mechanism will also be quickly destroyed by the flames and heat so as to release the bolt and permit the entry door to open.
Again, without other considerations, a most obvious answer to the problem of such lockset heat and flame destruction would be to form the entire lockset assembly of fire resistant material such as fire resistant steel. However, to form the lockset of fire resistant steel would involve extremely high material and other production costs making the resultant lockset marketable at such a high selling price so as to be usable in only a few instances and not by the general consumer. For instance, in locksets presently used by the general consumer, the knob assemblies include hollow knobs formed of brass since brass is relatively easily formed into many aesthetically pleasing decorative shapes and surface finishes, but a hollow brass knob will not withstand any great amount of flame and heat so as to be subject to quick destruction. To form these same lockset knobs of fire resistant steel would be cost prohibitive as stated.
Still another factor involved with the locksets used by the general consumer is that for economic production and assembly, standard lockset assemblies have permanently open entry paths from internally of the hollow knobs, through the knob assembly and into the internal confines of the door upon which the lockset is mounted. This means that there is an open entry path from internally of the knob directly into the bolt mechanism within the door, as well as to the lockset exterior doorlatch knob assembly of the door, so that destruction of the knob by heat and flames gives a direct flame path to the bolt mechanism and other lockset exterior components subjecting them to immediate severe heating which can result in partial or complete destruction. Any such severe damage to the lockset presents imminent danger of door release destroying the effect of a fire resistant door as hereinbefore discussed.